PCD and other superhard materials are well-suited for use in high temperature environments, such as those encountered when drilling wellbores into formations and may be used in cutters or other elements, such as erosion-resistant elements, on earth-boring drill bits. Diamond is extremely thermally conductive, but PCD often contains less conductive materials, such as metals. When the PCD is heated to a high temperature, the diamond conducts and dissipates heat much more readily than do any metals or other less thermally-conductive materials also in the PCD. This leads to a variety of problems that can damage or break the PCD. Accordingly, metals are often removed from all or a portion of the PCD, typically in an acid-leaching process.
Electrochemical processes have also been used to remove metals or other material from PCD. Electrochemical processes use an electrical current to remove electrons from some materials, such as metals found in PCD, to render those materials chemically charged (the materials form ions) and more able to dissolve in water or another liquid or gel and migrate out of the PCD as a result. The electrical current may also encourage the migration of ions out of the PCD. However, the same metals that are removed are also the primary way in which electrical current is conducted in the PCD because diamond is a very poor electrical conductor. The result of this combination of properties is the formation of a metal-free or reduced-metal layer of the PCD, which is not able to conduct an electrical current very well, and which, as a result, interferes with further progress of the electrochemical process.